AIO that I have black mold and property management is seemingly questioning whether or not it’s even mold?

For context, I live in an older building in Culver City and have lived here for 12 years. I’ve never really complained about much and all of the little things that need fixing I’ve just done on my own over the years. I finally reach out to property management because the black mold around my window sills continues to come back (I think it’s due to the fact that the windows in my apartment are so old and in the winter time there’s a ton of condensation and moisture either from rain getting in or the difference in temperature outside vs inside). I now have an almost 10 week old daughter and need this issue taken care of asap and they have stopped responding to me. Thinking of getting the city or a lawyer involved. Am I overreacting?